Fuel cells generate electric power by reacting hydrogen and oxygen in a fuel cell. Part of a fuel cell power plant is the fuel processing portion wherein hydrogen is generated.
A reformer reacts water and desulfurized hydrocarbon fuel in the presence of a catalyst to generate H.sub.2 CO and CO.sub.2. A low temperature shift converter reacts water and CO from the reformer producing additional hydrogen.
In the fuel cycle, raw fuel is first preheated for removal of oxygen in an oxidizer and for removal of sulfur in the hydrosulfurizer followed by H.sub.2 S removal. This preheat may use reformed gas from the reformer as the heat source.
Saturated steam from the plant accumulator is superheated for mixing with desulfurized fuel. This forms the mix to be supplied to the reactors of the reformer. Superheat of this steam is often accomplished with the heat exchange between the reformer exit gas and the steam.
Reforming the gas in the reactor is carried out in the presence of a catalyst as the product gas is heated by heat exchange with combustion products from a fired burner. Exhaust combustion gas from the reformer heat exchange is used to preheat air for its burner. In low temperature shift converters the catalyst must be maintained at a temperature level between 320.degree. F. and 500.degree. F. In operation, the reaction is exothermic and the hot gas must be cooled prior to and/or in the bed. During plant start-up the bed must be preheated to the minimum temperature.
A plurality of separate components are required for these many operations. A fuel preheat heat exchanger and an air preheat heat exchanger as well as a reformer and a reformed gas cooled heat exchanger is required. Also, a steam superheat heat exchanger is needed. Each unit has a footprint area, extensive outside surface requiring insulation, and connecting piping. The result is a large floor area, high heat loss, and many piping connections to be made as well as much surface to be insulated. Also, because of the high surface area there is a relatively high heat loss to the atmosphere.